It has been shown that tumor-derived DNA is present in the cell-free plasma/serum of cancer patients (Chen et al. Nat Med 1996; 2: 1033-1035). Most current methods are based on the direct analysis of mutations known to be associated with cancer (Diehl et al. Proc Natl Acad Sci USA 2005; 102: 16368-16373; Forshew et al. Sci Transl Med 2012; 4: 136ra68). But, such direct analysis of a panel of predetermined mutations to analyze has had a low accuracy in screening for cancer, e.g., by analyzing plasma DNA.
Further, such a direct analysis using a panel of predetermined mutations provides a limited view at the genetic make-up of a tumor. Thus, surgical biopsies are normally taken in order for sequencing to be performed on a tumor, to obtain genetic information about the tumor. The requirement of surgery increases risks and costs. Additionally, to find a location of a tumor, expensive scanning techniques are required before a surgical biopsy can be performed.
It is therefore desirable to provide new techniques to perform a broad screening, detection, or assessment for cancer, particularly in a noninvasive manner.